1. Field
The present invention relates to a washing machine and a method of controlling spin-drying thereof, and more particularly to a washing machine, which minimizes spin-drying errors generated by the excessive vibration of a tub in a spin-drying cycle, and a method of controlling spin-drying of the washing machine.
2. Description of the Related Art
In general, a washing machine (for example, a full automatic washing machine) is an apparatus, which includes a tub to contain water (washing water or rinsing water), a drum rotatably installed in the tub to contain laundry to be washed (hereinafter, referred to as laundry), and a motor to generate a driving force to rotate the drum, and removes contaminants from the laundry through a surface active action of a water current and a detergent.
The washing machine performs washing of laundry through a series of cycles including a washing cycle, in which contaminants of laundry are removed by water containing a detergent (specifically, washing water). The cycles also include a rinsing cycle, in which bubbles or the remaining detergent of the laundry are removed by water not containing the detergent (specifically, rinsing water), and a spin-drying cycle, in which the laundry is spin-dried at a high speed. In the spin-drying cycle when the drum is rotated at a high speed when the laundry is not uniformly disposed in the drum but is eccentrically loaded on one side in the drum, eccentric force is applied to a rotary shaft of the drum. Thus the drum is eccentrically rotated and collides with the tub to generate heavy vibration and noise.
Therefore, a liquid balancer (hereinafter, referred to as a balancer) to maintain the rotating balance of the drum is installed at the circumference of the drum, and maintains the dynamic balance of the drum, which is in the unbalanced state due to the imbalance of the laundry in the spin-drying cycle, thus reducing the vibration of the tub.
However, the washing machine including the balancer has a difference in the position of the balancer to maintain the dynamic balance of the drum due the position or amount of the imbalance of the laundry. A resonance point, where the tub is excessively vibrated before the balancer does not reach a balancing position to remove the imbalance of the laundry, is generated in the initial stage of the spin-drying cycle (approximately, 50˜80 RPM). The tub collides with an external case of the washing machine due to the excessive vibration of the tub and the overall washing machine is abnormally vibrated. Thereby, spin-drying errors are generated and thus the spin-drying cycle of the washing machine cannot be smoothly performed.
In order to solve the above problem, a checker switch to sense the excessive vibration of the tub generated by the imbalance of the laundry is conventionally installed between the case and the tub. When the tub strikes the checker switch due to the excessive vibration of the tub when the resonance point in the spin-drying cycle is passed, the spin-drying cycle is stopped, water is supplied to the drum to untangle the laundry, and then the spin-drying cycle is re-tried. However, this method increases a water consumption amount and lengthens a spin-drying time.